Situation
A global leader in the energy and infrastructure sector
Technical specifications of transformer:
Manufacturer: xxx
Year: 2012 (new)
Power [MVA]: 80
Voltage [kV]: 227/21/21
Oil mass [kg]: 26.700
Problem
Following an initial request to fill the new transformer, when the Sea Marconi technicians arrived they noticed there was free water inside the transformer.
This was due to the transformer not being properly sealed prior to transportation.
Solution
Sea Marconi carried out a rather complex operation in three separate stages:
- Dehydration of the papers by the direct “hot oil + vacuum” drying technique
This phase involves applying a vacuum to the transformer tank, filling it with hot oil to cover the windings, draining the transformer rapidly and repeating the process until the established values are achieved (water < 10mg/kg; dielectric strength > 70kV; amount of water extracted < 0.25 litre/24 hours). - Refilling and treatment
This phase involves applying a vacuum to the transformer tank, filling it with oil and subsequent physical treatment of the vents
The process took just over two weeks, during which 2.85 litres of water was extracted from the oil/transformer system.
